After the bomb blast at the Boston Marathon that took most of his legs, Jeff Bauman began his own long and painful journey.

BOSTON — Jeff Bauman stared straight ahead, his eyes wary and unconvinced, as his doctor told him the next procedure would be easy and painless. He sat in his wheelchair at Boston Medical Center, and Dr. Jeffrey Kalish, his primary surgeon, explained how a resident would remove the sutures from his legs.

Most of Bauman’s legs were gone. He had been waiting for his girlfriend near the finish line of the Boston Marathon on April 15 when the first of two bombs detonated and blew them off. An iconic sporting event had turned into a scene of chilling devastation, and a photograph of Bauman in the aftermath, his legs gruesomely lost, later became a searing symbol of the attacks.

The day of the bombings, Bauman had had an emergency, through-knee amputation that lasted about two hours. A surgeon had sifted through layers of skin, tissue and muscle, preserving what was healthy, cutting what was dirty and sick. He had removed what was left of Bauman’s lower legs at the knee joints.

Two days later, Kalish had performed a formal amputation at about four inches above the knee. He had measured the legs and cut each layer — skin, tissue, muscle and bone — farther up in the thigh, like a staircase. Then he washed out the legs for 10 minutes, tucked the muscle, and stitched the tissue.